The disclosure relates to a vertical separator for separating a fluid stream into a liquid phase stream and a gas phase stream. More particularly, the disclosure relates to a method for fabricating a helix of the vertical separator.
Separators are commonly used at subsea fields to separate produced wellbore fluids into gas and liquid streams. Many of these separators include a helix assembly. The helix assembly has an intermediate casing, an inner casing concentrically disposed within the intermediate casing, and a helix connected therebetween. The helix extends normally from each of the intermediate and inner casings and spans their lengths in a spiraling fashion.
During operation, a fluid, such as a two-phase wellbore fluid, is injected through a port in the upper end of the intermediate casing into the annulus between the intermediate and inner casings. Due to gravity, the fluid is routed over and along the helix toward the lower end of the annulus. As the fluid travels, the liquid phase moves toward the lowest point of the helix at the wall of the inner casing due to its density. At the same time, the gas phase moves to the highest point of the annulus, also due to its density. In this manner, the liquid and gas phases are separated from the fluid as it passes over and along the helix. Gas and liquid are subsequently conveyed from the separator in separate streams.
Once the gas phase is separated from the fluid passing over the helix, it is critical to the effectiveness of the separator that they remain separated and do not inadvertently re-mix. For this reason, the connections between the helix and intermediate casing and between the helix and inner casing should be fluid tight to prevent remixing of the fluid with the separated gas. Accordingly, means which enable such fluid tight connections are desirable. It would be particularly advantageous if such means enable ease of helix assembly fabrication.